I have the same hardware - iPhone 6 and iPad Air with a 2012 Mac - suggest you let iOS 10 settle and keep the devices connected to wifi for a while so they can complete any sync that needs to be done in the background - also update all your apps etc.

I have over 4000 contacts that took a while to sync - everything worked fine once everything was given time to complete.

I have the same hardware - iPhone 6 and iPad Air with a 2012 Mac - suggest you let iOS 10 settle and keep the devices connected to wifi for a while so they can complete any sync that needs to be done in the background - also update all your apps etc.

I have over 4000 contacts that took a while to sync - everything worked fine once everything was given time to complete.

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